Typically, hand blenders are versatile appliances, capable of supporting and driving various attachments and/or accessories designed to perform various tasks, such as whisking, blending or chopping, for example. In general, these attachments and accessories (generically referred to hereinafter for convenience as “tools”) are selectively attachable to (and removable from) a somewhat tubular main body part which houses an electric motor; this main body part being shaped and configured to be comfortably held in the hand of a user. The aforementioned tools tend to be generally tubular and elongate; indeed, wand-like, hence the expression which is often used to describe them. The tools, when selected for use, are attached end-wise to the main body part, so as to extend along the axis of the drive shaft of the electric motor, and each tool carries, at its end remote from the main body part, a respective processing head, containing blades or other devices, designed to cut, chop, comminute or otherwise process foodstuffs when the blade (or other device) is driven in rotation by the electric motor.
The speed at which the blade or other device of a given tool is driven will depend upon the function it is intended to perform. Thus some blades or other devices are driven at the full motor speed (typically 15,000 revolutions per minute (“rpm”) or thereabouts), whilst others are operated at lower speeds and thus require gearing. Lower speed operation may be required, for example, to provide additional operating torque for some functions and/or to reduce a risk of over-processing.
Where gearing is provided, it is preferable, though not essential, to incorporate it into the shaft of the tool, since the correct gearing is then certain to be in place when the tool is used. Alternatively, gearing may be provided in the motor housing, together with manually operable means to select the gearing appropriate to a chosen tool, or a separate gearbox may be provided, designed to be mounted between, and coaxially with, the tubular motor housing and the generally tubular tool.
Hand blenders are established, useful and versatile tools and at least those made by reputable manufacturers also conform to stringent safety requirements, designed to avoid user injuries through contact with the fast-rotating blades and the like. However, problems have been experienced when utilising existing tools in that:
(a) significant power levels may be required to effect certain processes;
(b) splashing or ejection of processed foodstuffs can occur during operation;
(c) strong vortices can be generated which tend to suck the blender tool down onto a receptacle in which the foodstuffs are being processed; and
(d) incomplete or protracted processing occurs because the foodstuff is not efficiently operated upon by the blade or other device.